Fluid measurement/division device and process

ABSTRACT

The fluid measurement/division device comprises a plurality of cylinders in which a first and a second piston are slidably inserted to operate alternately as a dosing piston or as a piloting piston for the dosing piston. The first and said second piston present reduced diameter regions which, together with the surface of the cylinders, define at least three constant volume distribution chambers and two variable volume pumping chambers. The device comprises a plurality of conduits connecting said cylinders together and to the outside, to allow or prohibit hydraulic connection in relation to the position assumed by the first and by the second piston, such that when the first piston is in the dosing stage and, by translating, it dispenses fluid and passes to the piloting stage, the second piston passes from the piloting stage to the dosing stage via a neutral stage.

FIELD OF THE INVENTION

The present invention relates to a fluid measurement/division device andprocess.

BACKGROUND OF THE INVENTION

In particular, the device and process of the present invention areusable to divide a fluid flow rate, for example to obtain from an inletflow two or more outlet flows of equal flow rate, with possiblemeasurement of the flow rate. If only one flow is obtained at the deviceoutlet, the device is used (and operates) as a flow rate measurementdevice, i.e. it exactly measures the delivered flow rate withouteffecting any flow rate division.

DISCUSSION OF THE RELATED ART

Devices of the indicated type are currently formed with at least threecylinders, in each of which a piston is slidably inserted.

Each piston is provided with two reduced diameter regions which definetwo distribution chambers inside the cylinder. Each cylinder alsodefines two pumping chambers at its ends.

The three cylinders are connected together by a plurality of conduits,such that the conduits alternately connect together one or other of thechambers defined between each cylinder and the respective piston.

During operation of the traditional device, each of the pistons is in adifferent operating stage.

In particular, while a first piston is in a dosing stage (and dispensesa predetermined quantity of fluid contained in a pumping chamber,forcing it to leave the device), a second piston is in a piloting stage(and causes the fluid to operate the dosing piston).

Finally a third piston is in a neutral stage, in which it does not acton the fluid (delivering it to the outside) and is not operated by thefluid; during this stage the piston contained in the cylinder in theneutral stage moves from the piloting position to the dosing position;if this stage were not present, the device would lock because the liquidwould not be able to continuously operate the pistons such that theyalternate their function by passing from the piloting stage to thedosing stage.

However, the described devices of traditional type are large and heavybecause of the minimum number of cylinder/piston pairs required fortheir operation; in this respect, at least three cylinder/piston pairsare required, each of which effects one of the described stages duringoperation, while the other cylinder/piston pairs effect the others.

The traditional devices are also costly to construct because of thelarge number of components required.

SUMMARY OF THE INVENTION

The technical aim of the present invention is therefore to provide afluid measurement/division device and process by which the statedtechnical drawbacks of the known art are eliminated.

Within the scope of this technical aim, an object of the invention is toprovide a device of small size and reduced weight; this advantageouslyenables devices to be constructed which can be handled and installedeasily, even in difficultly accessible or narrow positions.

Another object of the invention is to provide a device and process whichare economical to implement, in particular compared with traditionaldevices.

The technical aim, together with these and other objects are attainedaccording to the present invention by a fluid measurement/divisiondevice and process in accordance with the accompanying claims.

Advantageously, the device and process of the invention are also usablewhen the fluid which they are required to handle operates at high orvery high pressure (up to and beyond 2000 bar).

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the invention will be moreapparent from the ensuing description of a preferred but non-exclusiveembodiment of the fluid measurement/division device and processaccording to the invention, illustrated by way of non-limiting examplein the accompanying drawings, in which:

FIGS. 1-4 show a schematic view of the device in four differentsuccessive operating stages;

FIG. 5 shows a schematic view of a part of an end of a cylinder and of apiston slidable therein, in an embodiment of the device particularlysuitable for use with devices operating at high pressure;

FIG. 6 shows a schematic upper view of the device of the invention in adifferent embodiment;

FIG. 7 shows a schematic section through line VII-VII of FIG. 6;

FIG. 8 shows a lateral side view of the device of FIG. 6;

FIG. 9 shows a schematic section of the device of FIG. 6; and

FIG. 10 shows a particular of one way valves mounted on the outletconduits of the device of FIG. 6.

DETAILED DESCRIPTION OF THE INVENTION

With reference to said figures, these show a fluid measurement/divisiondevice indicated overall by the reference numeral 1.

The device 1 comprises two cylinders 2, 3 in which a first and a secondpiston 4, 5 are slidably inserted.

Each of the two pistons 4, 5 operates alternately as a fluid dosingpiston or as a piloting piston for the dosing piston.

The dosing piston dispenses fluid to the outside (by its movement),while the piloting piston defines the path for the fluid, which isdirected towards the dosing piston to control its movement.

Advantageously, the first and second piston 4, 5 present reduceddiameter regions which, together with the surface of the cylinders 2, 3,define three constant volume distribution chambers 6 a, 7 a, 8 a and twovariable volume pumping chambers 9 a, 10 a for the first cylinder 2, andthree constant volume distribution chambers 6 b, 7 b, 8 b and twovariable volume pumping chambers 9 b, 10 b for the second cylinder 3.

The device 1 comprises a plurality of conduits connecting the cylinders2, 3 together and to the outside (for example to interact with amachine), to allow or prohibit hydraulic connection in relation to theposition assumed by the first and second piston 4, 5.

Advantageously, with reference for example to FIG. 1, when the firstpiston 4 is in the dosing stage and translates to dispense fluid (arrowF1) to pass to the piloting stage, the second piston 5 is in thepiloting stage and passes to the dosing stage by passing through aneutral stage.

The neutral stage enables operation of the device of the invention to becontinuous in that, if it did not exist, the piloting piston would beunable to pass to the dosing stage and the device would lock.

As shown in the accompanying figures, the connection conduits comprise:a first conduit 11 to connect a first distribution chamber 6 a of thefirst cylinder 2 to a first distribution chamber 6 b of the secondcylinder 3, a second conduit 12 to connect a second distribution chamber7 a of the first cylinder 2 to a second distribution chamber 7 b of thesecond cylinder 3, and a third conduit 13 to connect a thirddistribution chamber 8 a of the first cylinder 2 to a third distributionchamber 8 b of the second cylinder 3.

The connection conduits also comprise a fourth conduit 14 to connect thefirst pumping chamber 9 a of the first cylinder 2 to the seconddistribution chamber 7 b or to the third distribution chamber 8 b of thesecond cylinder 3, a fifth conduit 15 to connect the second pumpingchamber 10 a of the first cylinder 2 to the first distribution chamber 6b or to the second distribution chamber 7 b of the second cylinder 3.

A sixth conduit 16 is provided to connect the first distribution chamber6 a or the second distribution chamber 7 a of the first cylinder 2 tothe first pumping chamber 9 b of the second cylinder 3, and a seventhconduit 17 to connect the second distribution chamber 7 a or the thirddistribution chamber 8 a of the first cylinder 2 to the second pumpingchamber 10 b of the second cylinder 3.

Finally, an eighth conduit 18 is provided to connect the firstdistribution chamber 6 a of the first cylinder 2 to the outside, a ninthconduit 19 to connect the second distribution chamber 7 a of the firstcylinder 2 to the outside, and a tenth conduit 20 to connect the thirddistribution chamber 8 a of the first cylinder 2 to the outside.

The device 1 suitably comprises a block 22 defining the first and secondcylinder 2, 3 and also at least the first, second and third connectionconduit 11, 12, 13.

In a preferred embodiment, shown in FIGS. 1-4, the block 22 also definesthe fourth, fifth, sixth, seventh, eighth, ninth and tenth connectionconduit 14-20.

The device advantageously defines a module provided with two cylinders.Several modules can be connected together, but in all cases thecylinders are operationally connected together in pairs.

The operation of the fluid measurement/division device of the inventionis apparent from that described and illustrated, and is substantially asfollows.

The fluid enters through the conduit 19 as indicated by the arrow F2 andis directed into the second chamber 7 b of the second cylinder (which isin the piloting stage).

In the second cylinder 3 the second piston 5 enables the fluid totransit through the fourth conduit 14 to enter the first pumping chamber9 a of the first cylinder 2.

This causes the first piston 4 to translate as indicated by the arrowF3; this translation causes the fluid contained in the second pumpingchamber 10 a of the first cylinder to pass through the fifth conduit 15,to pass through the first chamber 6 b of the second cylinder and throughthe first conduit 11, to be dispensed to the outside through the eighthconduit 18.

The device then assumes the configuration of FIG. 2.

In this configuration the first cylinder 2 acts as the pilotingcylinder, as the fluid enters the first conduit 2 (arrow F2) and isdirected into the second pumping chamber 10 b of the second cylinder 3(which operates as a dosing cylinder).

The second piston 6 then translates as indicated by the arrow F5, todispense the fluid contained in the first pumping chamber 9 b of thesecond cylinder 3 (as indicated by the arrow F1) through the sixthconduit 16 and the eighth conduit 18; the device then assumes theconfiguration shown in FIG. 3.

The fluid continues to enter through the ninth conduit 19 and passesthrough the second distribution chamber 7 a of the first cylinder 2 andthe second conduit 12 to reach the distribution chamber 7 b of thesecond cylinder 3 (which is in the piloting stage), in which the secondpiston 5 directs the fluid through the conduit 15 (arrow F6) and intothe second pumping chamber 10 a of the first cylinder, this lattertranslating as indicated by the arrow F7 to dispense the fluid containedin the first pumping chamber 9 a, as indicated by the arrow F8 (bypassing through the fourth conduit 14, the third conduit 13 and thetenth conduit 20); in this manner the device assumes the configurationof FIG. 4.

The fluid, which continues to enter the device through the conduit 19 asindicated by the arrow F2, enters the second chamber 7 a of the firstcylinder 2 (which operates as a piloting cylinder); in this cylinder thepiston directs the fluid into the sixth conduit 16 and then into thefirst pumping chamber 9 b of the second cylinder 3 (which operates as adosing cylinder).

The fluid entering the chamber 9 of the cylinder 3 causes the piston totranslate as indicated by the arrow F9, the fluid contained in it thenpassing through the seventh conduit 17 from which, via the third chamber8 a of the first cylinder 2, the fluid leaves the device through thetenth conduit 20 (as indicated by the arrow F8).

The device then returns to the configuration of FIG. 1 and the cyclerecommences.

A proximity sensor 26 is provided at each of the two ends of eachcylinder 2, 3 to sense the movements of the pistons 4, 5; this enablesthe dispensed fluid to be measured. A single sensor associated with eachcylinder could instead be provided.

It should be noted that in the time that passes between the commencementof movement of any one of the pistons and the moment in which it reachesits end-of-travel position, a sort of “neutral stage” occurs. In thisrespect, during this time interval, which can be varied either bystructurally modifying the valve or by modifying the piston movementvelocity, that piston not in movement is not piloted and remains at restin its original position.

An embodiment of the device of the invention is described hereinafterwith particular reference to FIG. 5 which is particularly suitable foruse in plants with fluids of high or very high pressure (up to andbeyond 2000 bar).

For high pressure use, traditional proximity sensors are unable to sensewhen the pistons 4, 5 reach the ends of the chamber (because of thelarge wall thicknesses required to resist such pressures).

In this respect, the block 22 defining the cylinders 2, 3 is provided atits ends with closure elements 25 associated with proximity sensorscomprising a sensing element 26 and a slider or element 27 slidable in achamber 28.

The slider or element 27 is made of magnetic material and is known tooscillate because it is drawn (arrow F14) by the sensor 26 when thepiston 4 is distant from the end of the cylinder 2, whereas when thepiston 4 is brought to the terminal end of the cylinder 2 the slider 27is drawn towards the piston (arrow F15).

In this manner the sensor 26 is able to sense (or count) the strokesundergone by the slider 27.

To enable the piston 4 (preferably made of ferromagnetic material but,in various applications, also of other non-ferromagnetic materials) todraw the slider 27, the pistons carry magnets 30 embedded in their ends,to cooperate with the corresponding sliders or magnetic elements 27 ofthe proximity sensors positioned at the cylinder ends.

In addition, to limit the negative effect on the magnetic forces causedby the large wall thickness, the pistons present convex ends, the coverelements 25 for the ends of the cylinders 2, 3 presenting recessed endsto receive the convex ends of the pistons 4, 5.

The present invention also relates to a fluid measurement/divisionprocess using the before described device.

The process consists of feeding the fluid to the piloting cylinder, inwhich the piloting piston defines (directing it thereto) that chamber ofthe dosing cylinder into which the fluid is to be fed.

The piloting piston translates to pass to the dosing stage, the dosingpiston translating to dispense the fluid and pass to the piloting stage.

In passing from the piloting stage to the dosing stage the pilotingcylinder passes through a neutral stage.

Modifications and variants in addition to those already stated arepossible.

Particularly, FIGS. 6-10 show a different embodiment of the device ofthe invention having the same features as those of the already describedembodiment.

In addition, the device is provided with one-way valves 35, 36respectively provided at the entrance of the outlet communicationconduits 18, 20; these valves allowing a more stable and homogeneousleaving fluid flow to be achieved.

Moreover, as shown in FIGS. 6, 7, 8, in order to sense or count thenumber of runs made by the pistons 2, 4, the device is provided withmagnets 37 placed at the end of adjustable supports 39 adjacent to everycylinder 2, 3 for example constituted by screws engaged in threadedholes of the block of the device.

The count of the runs of the pistons in this case is made by measuringthe perturbations of the magnetic field generated by such magnets 37.

In addition, in order to eliminate possible instability problems, thepistons 4, 5 of the device are asymmetric, so that they are formed withthe chambers of one piston staggered one another, in such a way that, inevery situation, the piston acting as a piloting piston opens itschambers before the other piston, which acts as dosing piston.

Finally, additionally or alternatively to the trick of staggering thechambers, the two pistons 4, 5 have different length one with respect tothe other and, particularly, one is shorter that the other of about 1millimetre.

It has been found in practice that the fluid measurement/division deviceand process of the invention are particularly advantageous because thedevice is extremely compact and lightweight.

The fluid measurement/division device and process conceived in thismanner are susceptible to numerous modifications and variants, allfalling within the scope of the inventive concept; moreover all detailscan be replaced by technically equivalent elements.

In practice the materials used and the dimensions can be chosen at willin accordance with requirements and the state of the art.

1. A fluid measurement/division device comprising a plurality ofcylinders in which a first and a second piston are slidably inserted tooperate alternately as a fluid dosing piston or as a piloting piston forthe dosing piston, wherein said first and said second piston presentreduced diameter regions which, together with the surface of saidcylinders, define at least three constant volume distribution chambersand two variable volume pumping chambers, said device comprising aplurality of conduits connecting said cylinders together and to theoutside, to allow or prohibit hydraulic connection in relation to theposition assumed by said first and by said second piston, such that whensaid first piston is in the dosing stage and, by translating, itdispenses fluid and passes to the piloting stage, said second pistonpasses from the piloting stage to the dosing stage via a neutral stage.2. A device as claimed in claim 1, wherein said connection conduitscomprise: a first conduit to connect a first distribution chamber of thefirst cylinder to a first distribution chamber of the second cylinder, asecond conduit to connect a second distribution chamber of the firstcylinder to a second distribution chamber of the second cylinder, athird conduit to connect a third distribution chamber of the firstcylinder to a third distribution chamber of said second cylinder, afourth conduit to connect a first pumping chamber of the first cylinderto a second distribution chamber or to a third distribution chamber ofsaid second cylinder, a fifth conduit to connect the second pumpingchamber of said first cylinder to the first distribution chamber or tothe second distribution chamber of said second cylinder, a sixth conduitto connect a first distribution chamber or a second distribution chamberof said first cylinder to a first pumping chamber of said secondcylinder, a seventh conduit to connect said second distribution chamberor said third distribution chamber of said first cylinder to said secondpumping chamber of said second cylinder, an eighth conduit to connectsaid first distribution chamber of said first cylinder to the outside, aninth conduit to connect said second distribution chamber of said firstcylinder to the outside, and a tenth conduit to connect said thirddistribution chamber of said first cylinder to the outside.
 3. A deviceas claimed in claim 1, further comprising a block defining said firstand second cylinder and said first, second and third connection conduit.4. A device as claimed in claim 2, wherein said block also defines saidfourth, said fifth, said sixth, said seventh, said eighth, said ninthand said tenth connection conduit.
 5. A device as claimed in claim 1,wherein said pistons carry magnets embedded in their ends, to cooperatewith corresponding magnets of proximity sensors positioned at the endsof said cylinders.
 6. A device as claimed in claim 5, wherein saidpistons have convex ends.
 7. A device as claimed in claim 6, whereinclosure elements for the ends of said cylinders present recessed ends toreceive said convex ends of said pistons.
 8. A device as claimed inclaim 1, wherein said device defines a module provided with twocylinders.
 9. A device as claimed in claim 1, further being providedwith one-way valves provided at the entrance of the outlet communicationconduits.
 10. A device as claimed in claim 9, further being providedwith magnets to sense or count the number of runs made by the pistons,each of said magnets being placed at the end of an adjustable support.11. A device as claimed in claim 10, wherein said pistons are asymmetricand are formed with the chambers of one piston staggered one another, insuch a way that in every situation the piston acting as piloting pistonopens its chambers before the other piston.
 12. A device as claimed inclaim 11, wherein the two pistons have different length one with respectto the other.
 13. A fluid measurement/division process using a devicecomprising a pair of cylinders, in each of which a piston slidespresenting three reduced diameter regions defining three distributionchambers and two variable volume pumping chambers connected together bya plurality of conduits, wherein it feeds the fluid to a pilotingcylinder in which the piloting piston defines that chamber of the dosingcylinder into which the fluid is to be fed, the piloting pistontranslating to pass to the dosing stage, the dosing piston translatingto dispense the fluid and pass to the piloting stage, in its passagefrom the piloting stage to the dosing stage said piloting cylinderpassing through a neutral stage.